Another Stupid 360 Question

[dbesade]

I'm shopping for parts right now, I'm looking at cast Sealed Power pistons P/N 362NP. They say the compression ratio is 9.0:1 with a compression distance of 1.581.

Anyone hear about these or have experience with them? They have them priced at $121...

Thanks

-Dave

[AMX69PHATTY]

These are for a 360 right ?
Pretty sure stated CR assumes milling the deck and heads .020
to get "stock" .012 deck clearance with .020 shorter pistons,
which then means the intake will need machined also.
Option is to offset grind the crank .010 or .020 then deck mill can be less.
This increases cubes and CR and also helps quench.
For ideal quench target a 0.000 deck clearance
which should be doable between offset grind and deck mill.
Pistons have a dish volume somewhere between 24cc & 30cc.
Those style pistons have been ok for me.

[dbesade]

:-| hmm I was hoping to get away without taking the heads and deck down.. hrm.. I will have to re-think this then. If needed I guess I will need to go with a stock style piston to avoid it.


-Dave

[AMX69PHATTY]

As far as I know, as wierd as it seems, no one makes a 360 piston with the stock compression height of 1.600 or a dish volume that will give a 9.5 or so CR which is what pretty much everybody wants, which is strange. This leaves as the only option getting custom forged pistons made to specs provided by the builder, and we're talking $700-$800 a set and maybe 3 months delivery along with the compromises that go along with using forged pistons. In doing some research it was found that EGGE Obsolete Engine Parts will produce cast pistons to a provided spec, but ( 10 ) sets must be ordered for them to do it. If I had the money, which I don't, I would order ( 10 ) sets of AMC 360 cast pistons with a 1.600 compression height and a 15cc to 20cc dish volume, probably 17cc as this would give approximately a 9.5:1 CR with 58cc heads. As far as I know all cast pistons available are like the Sealed Power units you mentioned, unless you find some discontinued new old stock. As of in the past couple years, all aftermarket cast piston production has been taken out of the USA and sent overseas.

111!!! Aint progress great ?

[dbesade]

Well, maybe we can get a group buy going here, between us and other amc forums, we should be able to get 10 people doing a 360 build...

I'm in for a set

-Dave

[AMX69PHATTY]

Just called'em, they said to email them with request for quote on price and delivery, but it would probably take 3 months once ordered. They have 343 4V and 2V pistons already listed under RAMBLER, ~$300 a set, but they are 1.578 compression distance and the 4V is a flat top with valve reliefs, and the 2V has a ~8cc dish. See a post here by Painted_Rat, he just built a 360 using the Egge 343 4V Flat Tops, they end up ~.040 down in the hole. he also had to grind a small relief on the bottoms below the pins to clear the crank counterweights. JeepsR4ever also sated some "concerns" with quality. The 343 pieces are "better" than the huge dished pieces, but aint "right" due to the "short" Compression Height, need 1.600 for good quench, then on a 360 .012-.015 deck mill would yield 0.000 deck clearance and .045 nominal quench.